DSCC Executive Director Guy Cecil said he sees the donations as a sign that Democratic donors are anticipating the 2014 midterm elections.

"Our supporters didn't need any more motivation to hold the Senate, but they got more anyway when the Republican 'War on Women' grabbed headlines again this month," Cecil said.

"The thought of Mitch McConnell becoming majority leader is enough to motivate most Americans to support our efforts, and we continue to break fundraising records. We still have a very long road to travel, but we are off to a strong start," he added.

During the first four months of the year, Senate Democrats raised more than $17.2 million, while the National Republican Senatorial Committee raised $10.4 million, according to figures reported to the Federal Election Commission.

The NRSC has not released its May fundraising numbers yet. The Senate GOP campaign organization had $7.1 million in the bank and $9.5 million in debt by the end of April.

The DSCC has not disclosed its current debt figures, but owed almost $13.8 million at the end of April.

The Democratic Senatorial Campaign Committee raised $4.9 million in May, bringing its fundraising so far for 2014 to an impressive $22.2 million, Politico reports. According to DSCC officials, that is its best May during a non-election year.